A filled shell would have " doubly magic " ( both its proton number of 114 and neutron number of 184 are thought to be magic ) and thus the most likely to have a very long half-life . ( The next lighter doubly magic spherical nucleus is lead-208, the heaviest known stable nucleus and most stable heavy metal .)
22.
Because, for even " Z " ( proton number ) and even " N " ( neutron number ) nuclei, there is a gap from ground state to first excited particle state which is reached by nucleon pair breaking fragments with even " Z " is expected to have a higher probability to be produced than those with odd " Z ".
23.
Of particular note is Ubh-310, which would be " doubly magic " ( both its proton number of 126 and neutron number of 184 are thought to be magic ) and thus the most likely to have a very long half-life . ( The next lighter doubly magic spherical nucleus is lead-208, the heaviest known stable nucleus and most stable heavy metal . )"
